It is known to die cast or squeeze cast a variety of hollow metal castings utilizing expendable cores which are subsequently removed from the casting to leave voids therein. Expendable cores may comprise any of a variety of materials which can withstand the heat of casting but can be readily removed thereafter. Common such cores comprise salt, resin-bonded sand or the like. Following casting and solidification of the metal, the expendable core is removed, e.g., by dissolution for salt cores or vibration for sand cores. Expendable cores have been used to cast a variety of products including blocks for liquid-cooled internal combustion engines.
It is essential that the cores be precisely located and securely anchored in the die cavity in order to cast the part to the proper dimension, and to preclude any shifting of the core during the introduction of the metal. The proper positioning and anchoring of the cores in the die cavity can be a complicated procedure particularly in the manufacture of internal combustion engine blocks having cooling jackets in close proximity to the combustion chamber and separated therefrom by only a thin wall of metal. One technique for mounting expendable cores for use in forming cooling jackets in engine blocks is disclosed in Koch U.S. Pat. No. 4,981,168. Koch provides a resin-bonded sand core having a print-out portion at one end thereof which is adapted to fit into a core print in one of the die parts. A mandrel used to form the block's combustion chamber(s) has a flange(s) thereon which holds the print-out in place in the core print. Locating pins extend into the print cavity for bridging any gap between the print-out portion of the core and the print cavity in the die hence eliminating any "loose fit" therein. The mandrel may hold a cylinder liner (e.g., a cast iron sleeve for use with an aluminum block), and is adapted to fit over a dowel provided in one of the die parts. The mandrel is clamped in the die between two opposing die parts. The core and mandrel are assembled outside of the die before being placed on the dowel. After casting, the mandrel remains with the casting until it is removed and reused. For forming engine blocks having plural combustion chambers, a secondary mandrel frame is provided which supports a separate mandrel for each cylinder and a plural-cylinder core.
It is an object of the present invention to provide an uncomplicated method and apparatus for simply, quickly and accurately positioning an expendable core in a die casting die, and anchoring it therein against movement during the casting cycle.
It is a further object of the present invention to provide such a method and apparatus for positioning and anchoring an expendable sand-core in the formation of a cooling jacket in an internal combustion engine block. These and other objects and advantages of the present invention will become more readily apparent from the detailed description thereof which follows.